1. Field of the Invention
This invention generally relates to electrochemical cells and, more particularly, to a flow-through air cathode battery using a zinc slurry anode with a carbon additive, complexing agent, and auxiliary water source.
2. Description of the Related Art
Flow-through batteries has been intensively studied and developed for large-scale energy storage due to their long cycle life, flexible design, and high reliability. A battery is an electrochemical device in which ions (e.g. metal-ions, hydroxyl-ions, protons, etc.) commute between the anode and cathode to realize energy storage and conversion. In a conventional battery, all the components including anode materials, cathode materials, separator, electrolyte, and current collectors are packed into a volume-fixed container. Its energy and capacity of are unchangeable as long as the battery is assembled. A flow-through battery consists of current collectors (electrodes) separated by an ion exchange membrane, while its anode and cathode materials are stored in separate storage tanks. The anode and cathode materials are circulated through the flow-through battery in which electrochemical reactions take place to deliver and to store energy. Therefore, the battery capacity and energy are determined by (1) electrode materials (anolyte and catholyte), (2) the concentrations of anolyte and catholyte, and (3) the volumes of anolyte and catholyte storage tanks.
An air battery may be considered to be a flow-through cathode battery where oxygen in the air is continuously passed over a reactive metal electrode to act as a cathode. An electrolyte typically separates the cathode from a metal or a metal compound anode. Zinc is a favored material, and it may be in a solid phase or in a particle form to enable a flow-through anode. Conventional batteries using a flow-through zinc particle anode suffer from the large amounts of electrolyte required to avoid passivation around zinc particles. Further, the zinc particle anode requires continuous pumping, and the viscosity needed to support pumping results in a low zinc concentration.
It would be advantageous if a flow-through zinc anode battery existed that used a low viscosity slurry with a high concentration of zinc.